2 - 15 Extraction and uses of metals
● ***Minerals: metals combined with other elements (as individual compounds),
existing in natural form in Earth’s crust
● ***Ore: sample of rock containing enough of mineral to be worth to extract the metal
● Unreactive metals (e.g.: gold) are found native, existing naturally as uncombined
element
● ***Roasting: (easy) conversion into oxide by heating in air, e.g.:
2ZnS (s) + 3O2 (g) → 2ZnO (s) + 2SO2 (g)
● ***To obtain metal from metal oxide, need to remove the oxygen (i.e.: needs to be
reduced)
Methods of extraction and the reactivity series
● Cost of energy and cost of reducing agent matters
● Metals below carbon in reactivity series, cheapest method of reducing ore is
heating with carbon
● E.g.: Fe2O3 (s) + 3C (s) → 2Fe (l) + 3CO (g)
(SBA) 2Fe2O3 + 3C → 4Fe + 3CO2 [immediate equation]
●
1
, ●
● Metals above zinc cannot be reduced using carbon, as they are more reactive
than carbon, therefore carbon cannot take oxygen away from metal oxide, need
to extract by electrolysis
2
● ***Minerals: metals combined with other elements (as individual compounds),
existing in natural form in Earth’s crust
● ***Ore: sample of rock containing enough of mineral to be worth to extract the metal
● Unreactive metals (e.g.: gold) are found native, existing naturally as uncombined
element
● ***Roasting: (easy) conversion into oxide by heating in air, e.g.:
2ZnS (s) + 3O2 (g) → 2ZnO (s) + 2SO2 (g)
● ***To obtain metal from metal oxide, need to remove the oxygen (i.e.: needs to be
reduced)
Methods of extraction and the reactivity series
● Cost of energy and cost of reducing agent matters
● Metals below carbon in reactivity series, cheapest method of reducing ore is
heating with carbon
● E.g.: Fe2O3 (s) + 3C (s) → 2Fe (l) + 3CO (g)
(SBA) 2Fe2O3 + 3C → 4Fe + 3CO2 [immediate equation]
●
1
, ●
● Metals above zinc cannot be reduced using carbon, as they are more reactive
than carbon, therefore carbon cannot take oxygen away from metal oxide, need
to extract by electrolysis
2
